orget about oceans of calamine lotion, this is the real dirt on poison ivy and all of its kin. Susan Pell, executive director of the United States Botanic Garden. She did her PhD on members of the pistatchio family (Anacardiaceae), which includes the genus Toxicodendron, of which poison ivy, poison oak and poison sumac are members. Shauna Dobbie, editor of Canada’s Local Gardener magazine, had a talk with Susan about these plants: how to identify them, what gives you a rash, and what you can do about it.